The dwindling supplies of known petroleum and natural gas reserves have led to a search for alternate energy sources. Oil shale, because of its great abundance, is considered one of the primary sources of liquid fuels to supplement and replace those now obtained from petroleum.
Generally, shale oil is produced or recovered from oil shale by pyrolysis. A number of different processes are known for recovering shale oil from the oil shale or sedimentary rock. While the liquid products derived from oil shale by these techniques represent products of somewhat differing but suitable quality, they generally require further upgrading and processing before they can be employed as feedstocks in conventional refining operations. One of the problems involved in working with such liquids is the presence of finely divided solids, particulate and dust. These solids or fines have been typically removed from shale oil by a process called dedusting. In this process solids are removed from shale oil by addition of water to the shale oil and then subjecting the mixture to an electrostatic field to resolve it into a dedusted shale oil phase and an aqueous phase which carries the finely-divided solids.
Another problem associated with the liquid fuels derived from oil shale is their poor stability characteristics. Instability in such fuels is generally manifested by the formation of large quantities of sediment or gum during storage. It has been known to stabilize shale liquids by hydrotreating. This technique which involves either the removal of unstable species or converting them to stable compounds, while generally suitable, requires an additional process step which can be expensive.